Advanced ceramic materials are commonly utilized in systems located in hostile environments, such as, for example, automotive engines (e.g., catalytic converters), aerospace applications (e.g., space shuttle titles), refractory operations (e.g., firebrick) and electronics (e.g., capacitors, insulators). Porous ceramic bodies are of particular use as filters in these environments. For example, today's automotive industry uses ceramic honeycomb substrates (i.e., a porous ceramic body) to host catalytic oxidation and reduction of exhaust gases, and to filter particulate emissions. Ceramic honeycomb substrates provide high specific surface area for filtration and support for catalytic reactions and, at the same time, are stable and substantially structurally sound at high operating temperatures associated with an automotive engine environment.
In general, many of today's advanced porous ceramic bodies are formed out of composite ceramic materials (i.e., a combination of different ceramic materials and/or phases of ceramic materials). Composite materials allow for tailoring a material's characteristics for a particular use. That is, two or more different materials and/or phases of a single material can be combined to produce a resulting composite material, which has material characteristics controlled by the proportions and locations of the different materials and/or phases used to form the composite. As a result of using composite materials in hostile environments, such as, for example, extreme temperature environments, cracking may result due to differences in thermal expansion characteristics of the combined materials. In addition, unwanted expansion of a high coefficient of thermal expansion material within the composite can also occur causing design restraints and inefficiencies.